The Timer service (javax.management.timer) is unnecessarily hard to use. First of all, the addNotification method requires you to supply a notification type, and most users neither know nor care what to put there. In fact you can probably get away with putting null there, but the documentation should say that explicitly, and it should suggest a "jmx.something" string that you can use as well.

Secondly, it would be good if the documentation explained how to have different listeners for different notifications, when you have several notifications triggered off the same timer. See <http://forum.java.sun.com/thread.jspa?forumID=537&threadID=749048>.